Change "nil" to "NULL"
Use integer types with explicit widths

Replace types like "unsigned char" and "ushort" with <stdint.h>
types like uint8_t.

Remove uchar/ushort/uint/ulong from autoconf.
Move method return type to declaration line

Having the method name up against the left edge used to be common
practice, because you could jump to a method quickly by searching
for "^name".  Now we have "ctags" and IDEs.
Fix include guards

Symbols starting with "__" are reserved for use by the compiler.
Version bump to 2.3.0